The objective of this proposal is to better understand the characteristics of the stable hypertrophied myocardium encountered in the course of many correctable lesions, to investigate sudden death in hypertrophy and to study the response to impaired myocardial oxygen delivery. A major thrust will be a systematic investigation of alterations in myocardial function during stable hypertrophy and its transition to failure, and of the effects of cardiopulmonary bypass with various methods of myocardial preservation on functional characteristics of the stable hypertrophied heart. The long-term goal is to improve understanding of the pathophysiology of cardiac disease and the treatment of patients suffering from it. Work will be divided into several closely interrelated component areas: 1. Physiologic and biochemical characteristics of hypertrophy. (a) Global and segmental left ventricular function in hypertrophy. (b) Regional distribution of myocardial blood flow in hypertrophy with stress. (c) Response of the stable hypertrophied heart to drugs; digitalis, catecholamines. (d) Catecholamine content of the hypertrophied myocardium. 2. Hypertrophy and sudden death: changes in myocardial characteristics with severe stress. 3. Effect of cardiopulmonary bypass on the hypertrophied heart. (a) Methods of myocardial preservation during intracardiac surgery. 4. Response of the hypertrophied heart to altered myocardial oxygen delivery: (a) Anemia (b) Coronary stenosis. 5. Study of the changes, factors and mechanisms in the transition from hypertrophy to failure. (a) Combination of pressure and volume overload. (b) Failure developing late in the natural course of hypertrophy.